Automatic drilling machine



Aug. 16, 1949. w, B Ess 2,479,293

AUTOMATIC DRILLING MACHINE Filed July 12, 1945 v7 Sheets-Sheet 2 WILLIAM T. BAYLEss WW ATTORNEY Aug. 16, 1949. w. T. BAYLESS' 2,479,293

AUTOMATIC DRILLING MACHINE Filed July 12, 1945 7 Sheets-Sheet 4 65 FIGIO 67 47 36 I /7 LIN FIGII 46 2o" /0 l I j WILLIAM T BAYLEss BY mtuww ATTORNEY INVENTOR:

Aug. 16, 1949. w BAYLESS 2,479,293

AUTOMATIC DRILLING MACHINE Filed July 12, 1945 '7 Sheets-Sheet 5 INVENTOR'. WILLIAM T BAYLESS BY W W ATTORNEY Aug. 16, 1949B w. T. BAYLESS 2,479,293

AUTOMATIC DRILLING MACHINE Filed July 12, 1945 7 Sheets-Sheet 6 M8 KY9 I85 lNVENTOR: WILLIAMTBAYLESS BY W ATTORNEY Aug. 16, 1949.

Filed July 12, 1945 W Fwv. RELAY.

W. T. BAYLESS AUTOMATIC DRILLING MACHINE BYI 7 Sheets-Sheet 7 INVENTOR WILLIAM T. BAYLESS ATTORNEY.

Patented Aug. 16, 1949 UNITED STATES PATENT OFFICE AUTOMATIC DRILLING MACHINE William T. Bayless, Swissvale, Pa.

Application July 12, 1945, Serial No. 604,543

7 Claims. (01. 77-5) This invention relates in general to certain new and useful improvements in automatic drilling machinery and, more particularly, to an automatic drilling machine adapted for drilling a relatively large number of holes through stacks of sheet metal or similar material of large area.

In a number of industrial operations, it is necessary to drill large numbers of holes of a predetermined size at many different points over a substantially large area. For example, in making wing struts, skin sections, and other component structural parts of large airplanes, thin aluminum sheets must be marked according to patterns and large numbers of rivet holes made in the sheets at the points indicated by the pattern. At the present time, these operations are performed largely by hand with manually operated drill presses. In some cases, a stack of sheets will be clamped upon a large table and drilled by a hand-operated electric drill mounted upon a long elbowed beam which swings over the table and permits the operator to locate the drill at any desired position. Obviously such expedients are inefiicient and time-consuming, as well as inexact. Because of the large area of the sheets being drilled, it is very diflicult for an operator to locate the drill point accurately with reference to the markings transferred from the pattern. This is particularly true in the central area of the sheet where the workers line of sight must necessarily be oblique rather than direct.

It is, therefore, the primary object of the present invention to provide an automatic drilling machine which is capable of drilling any number of holes over a relatively wide and extensive area and at any number of selected points in a speedy, precise, economical manner and under full and entire automatic control without intervention of the operator.

It is a further object of the present invention to provide a machine of the type stated which is substantially rugged and durable in construction and will withstand severe commercial usage and will result in substantial time-saving in the performance of drilling operations.

And with the above and other objects in View, my invention resides in the novel features of form, construction, arrangement, and combination of parts presently described and pointed out in the claims.

In the accompanying drawings (seven sheets) Figure 1 is an end elevational view of an automatic drilling machine constructed in accordance with and embodying the present invention;

Figure 2 is a fragmentary top plan view of the automatic drilling machine;

Figure 3 is a fragmentary side elevational view;

Figures 4 and 5 are top plan views, respectively, of two diflerent types of templates used with, and forming a part of, the present invention;

Figures 6, '7, 8 and 9 are vertical sectional views of the drilling head mechanism in four difierent positions, respectively, illustrating the full cycle of operation thereof;

Figure 10 is an end elevational view of the drilling head mechanism;

Figure 11 is a schematic wiring diagram showing the various electrical connections between the several component parts of the automatic drilling machine;

Figure 12 is a vertical sectional view of a resetting switch forming a part of the present inven tlon;

Figure 13 is a top plan view of a modified form of automatic drilling machine constructed in accordance with and embodying my present invention;

Figure 14 is a fragmentary sectional View of the modified form of drilling machine shown in Figure 13 and illustrating in large detail the direction controller-indicator forming a part of this invention;

Figure 15 is a side elevational view, partly broken away and in section, of the central control switch forming a part of the present invention;

Figure 16 is a transverse sectional view of the central control switch taken along line lS-IB of Figure 15;

Figure 17 is a detailed showing of the directional control element; and

Figure 18 is a schematic wiring diagram showing the electrical connections of the embodiment illustrated in Figure 13.

Referring now in more detail and by reference characters to the drawings, which illustrate practical embodiments of the present invention, A designates a table consisting of a relatively large fiat top I supported by a plurality of legs 2. Rigidly mounted upon the upper face of the top I and extending lengthwise thereof adjacent, and in inwardly spaced relation to, the longitudinal margins thereof, are track-forming rails 3 having upstanding webs 4. It will, of course, be understood that the table A may be of any desired size or shape, depending upon the requirements of the particular production operations to be performed. For airplane manufacturing plants, an oblong rectangular table approxiof, and connected by, two transversely extend W ing spaced parallel beams 6, I. Mounted in and extending through the flanges of the channel bars 5, 5', adjacent the ends thereof, are horizontal shaft bearings 8, 8', 9, 9, the bearings 8, 8', being located in co-axial alignment and the bearings 9, 9', also being located in co-axial alignment for respectively receiving and sup-- porting shafts I 0, I, projecting axially therethrough. and, in turn, provided -,at their outer ends with pairs of wheels H, H, having'peripheralgrooves l2. for engagement with the track webs 4. 1

' Bolted or otherwise suitably secured at its ends upon the upper faces of the channel members 5, is atop plate 13- having its one margin m spaced inwardly from, and extending parallel to, the shaft l0" and being cut away at one end to provide a slot-like recess 8. Mounted upon the under. face of, and depending fronnthe plate I3, is a carriage motor l4 having a horizontal shaft l5 disposed in parallel relation tothe shafts l0, l0, and provided at its ends with a rubbertired. driving wheel H; of sufficient diameter for peripheral engagement against the upper face of the table top I whereby to propel the entire carriage to and fro along the tracks 3-. 'For purposes of clarity, the wiring and connection with the motor, as well as the other elements of electrical equipment hereinafter referred to, will be presently described in connection with the detailed discussion of the wiring diagrams and circuits employed.

J ournaled at its ends in, and extending horizontally between, the channel members 5, 5', in horizontal alignment with the shaft [0, is a-lead screw I! provided at one end with a pulley l8, whichin turn, extends upwardly through a slot sand which is drivingly connected by a belt'lll to a driving pulley operatively mounted on the shaft of a traversing motor 2|. I

' Provided'for transverse or so-calledtraversing movement crosswise-of the carriage B, is a drill frame 22 comprising an integral casting including a central collar 23 and; two diametrically opposite horizontal members 24, 24', The member 24 is. internally bored and machined to fit slidably uponv and around the shaft Ill and the member 24 is similarly bored to receive a horizontally shiftable sleeve 25 projecting at its ends for ashortdistance beyond the ends of the member 24 and being provided on such projecting ends with set-collars 26 and spring-washers. 2-6, the

latter beingdisposed between the set-collars 26 and the end-faces of the member 24' so as to introduce aslight amount of end-play between the sleeve 25 and the member 24. The sleeve 25 internally threaded for engagement with the lead screw H in such a manner that, as the lead screw H is rotated, the drill frame 22 will be shifted or traversed crosswise, Also formed integrally with the collar 23 and extending radially therefrom approximately midway between the members 24, 24', is a vertically disposed 4 sleeve 21 integrally provided at its lower margin with a U-shaped yoke 28 having a horizontal bight 28, which is vertically bored in alignment with the internal bore of the sleeve 21.

Slidably mounted in the collar 23 on the drill frame 22, is a tubular drill head 29 provided with a plurality of longitudinal splines 30 for engagement with suitably milled slots 3| in the collar 23, so that the drill head 29 may shift Vertically up and down relatively to the collar 23 without rotating therein. The drill head 29 is provided at its upper and lower ends with a pair of vertically aligned radially projecting arms or extensions 32, 33, which are, in turn, provided at their outer ends with vertically aligned shaft bearings 31, 35. Formed integrally with and extending above and over the arm 33, is an auxiliary yoke 36 having the shape of an inverted U and including a flat bight portion 31 disposed in upwardly spaced parallel relation to the arm 33 and provided with a vertical shaft bearing 38 aligned with the shaft bearings 34, 35. The arm 33 and the bight 31 are also provided with a pair of vertically aligned shaft bearings 39, 40,. disposed radially inwardly from the shaft bearings Rotatably mounted at its ends in and extending vertically between the: bearings 34, 35, is a drill-locating shaft M provided at its lower end 7 with a fast-running thread or groove 42 adapted for threaded engagement in a gear nut d3, which is, in turn, mounted between the sleeve 21 and the bight 28' of the drill frame collar 2'3 and is of such diameter as to project outwardly therefrom along its periphery for engagement with a driving gear 44 pinned to the shaft 45 of an electric motor 15 bolted upon the outwardly presented face of the sleeve 2?, At its upper end, the shaft 4! is, reduced in diameter and extends through the bearings 35, 38, and is provided therebetween with a spur gear 41, which is pinned thereon and meshes with a spur gear 48 pinned to a dril'l'fced shaft 49 rotatabiy mounted at its lower end in the bearing 39 and extending upwardly through and above the bearing 49. On its extended end, the shaft 49 is provided with a slow-running thread or groove 50 for engagement in an internall-y threaded nut 5i formed in the outer end of a feed arm 52, which is, at its other end, rigidly bolted upon the upper end face of a drill motor 53.

The drill motor 53 is circularly machined around its outer cylindrical face to fit snugly within the tubular head 29- and is provided with a plurality of radially projecting vertical splines 54 for slidably fitting engagement within slots 55 milled in the inner face of the head 29. At its lower end, the drill motor is conventionally provided with a downwardly projecting drill. chuck 56 having suitable jaws 51 for receiving a drill point 58. Removably threaded upon the lower end of the head 29-, is a conically shaped drill shield 5-5 provided at its lower end with a selfcentering tubular extension having an internal diametrical size sufficiently larger than the drill point 58 to permit the drill point 58 to pass freely therethrough.

Mounted by means of a suitable: upwardly projecting arm 6i upon the upper end of the drill head 29, are a reversing switch SM and a doublepole single-throw switch S102, respectively having extended toggle arms 62, 63, positioned for actuating co-operation with kick lugs 64, 65, projecting outwardly from a switch-actuating arm 66 mounted rigidly upon the upper end of the drill motor housing 53.

Also mounted by means of a suitable frame 61 upon the upper and outer ends of the drill frame arm 33, is a resetting switch S103 comprising a switch housing 68 provided internally with a fixed or stationary solenoid winding 69. Reciprocably mounted in the solenoid winding 68, is a bar provided at its outer end with a conductive cross arm H, which is, in turn, provided at its outer ends with contact points I2, I3, located for engagement with contact points I4, 15, the latter being mounted by means of conventional insulators upon a convenient side wall of the housing 68. At its other end, the bar 10 is engaged with one end of a compression spring 16, which, at its other end, is mounted upon the housing 68. Along its projecting end between the solenoid 6S and the cross arm H, the bar 10 is provided with a detent recess 11 for engagement with the upper end of a vertically mounted latch bolt 18, which is normally urged upwardly by a compression spring 19 and, at its lower end, is pinned to one end of a latch actuating lever 88 fulcrumed or pivoted in a suitable boss 8| 0 the latter being normally urged upwardly by a leaf spring 84 into abutment against a stop pin 85. Interiorly of the housing 68, the solenoid 69 is connected by conventional leads to two binding posts 86, 81, and the conductive cross arm H is connected by a conventional flexible lead to binding post 89.

The coils of the solenoid 68 are so wound and connected that, when the solenoid is energized, the bar 18 will be shifted to the left (reference being had to Figure 12) against the pressure of the spring 15 until the detent recess 11 is aligned with the latch bolt 18. Thereupon, the latch bolt #8 will be urged upwardly by the spring 19 into engagement with the detent recess 11, thereby holding the bar 10 in such shifted position in which the contact point" is out of contact with the contact point M, and the contact point 13 is in contact with the contact point 15, and the switch may be said to be latched in open position. The resetting switch S103 is so positioned upon the frame 61 that the tongue 83 will be in the path of and engaged by a horizontal projection formed on the drill feed arm 52 so as to be tripped only by upward movement of the latter.

Mounted upon the upper face of the carriage plate 13, is a dynamoelectric amplifier Si or "amplidyne generator, which, as is well known to those skilled in this art, consists of a D. C. motor 9|, the drive shaft of which is directly coupled to the armature of a D. C. generator 9l the windings of which are suitably sh0rt-circuited and connected to produce a relatively large power output which is directly proportional to and controlled by a very small variable excitation current. Also mounted upon the upper face of the carriage plate I3, is a double throw relay 92 having two pairs of poles 92 92 and 82, 92 Similarly mounted upon the upper face of the carriage plate I3 is a two-pole circuit breaker 93, a reversing switch 94, and a two-pole single throw circuit breaker 95. The reversing switch 94 is so positioned upon the plate [3 as to project outwardly therefrom and is provided at its outer end with a projecting switch actuating arm 96, which is, in turn, positioned for engagement against upstanding abutment members 81, 91, the latter being rigidly mounted upon the table A and located in such a position that, when the carriage approaches either end of the table, the arm 96 will be pushed inwardly and the reversing switch 94 actuated so as to reverse the polarity of the leads passing therethrough, as will be presently more fully described.

Mounted on and carried by the drill frame 22, are two photoelectric cell units 6 0 conventionally comprising downwardly directed light sources 98, 99, and photoelectric cells I 00, IN, the light source 98 and the cell or so-called electric eye 88 being arranged in relation to each other, so that the beam of light from the source 98 will impinge upon and be reflected from suitably placed targets into the photoelectric cell 388. Similarly, the light source 99 and photoelectric cell I81 are arranged in relation to each other, so that the beam of light from the light source will impinge upon and be reflected from a suitable path-defining or guiding band.

Provided for co-operation with the photoelectric units 6 e is a template T for superposition upon the stack of work sheets resting upon the table A. It will, of course, be understood that the template T must be suitably designed for the particular work being done. Figure 4 a template is shown which is designed for a piece of work in which a plurality of holes are drilled in a series of straight parallel lines. Hence the template is provided with a series of spot-shaped targets 15, each one of which is adjacent to and associated with one particular hole which is to be drilled in the work and the template T is provided with an upwardly flaring or somewhat conical aperture h of such size and dimension that the self-ccntering projection 60 of the drill shield 59 will enter therein and serve to center the drill accurately within the limits of end play provided for between the sleeve 25 and the collar-member 24'.

The template T is also provided with a pathdefining band b, which is preferably spaced approximately equidistantly on the opposite side of the apertures h from the targets t. Because of the characteristics of the controls in this particular embodiment of the present invention, it is necessary to provide the template T with two so-called end zones Z1, Z2, which are beyond the transverse margins of the sheet and serve to reverse the lengthwise direction of movement of the drill carriage B and at the same time traverse the drill frame 22 transversely to the next transverse distance to the line Y and then proceeds outwardly in a lengthwise direction across the table to take up its required directional path, all as best seen in Figure 2. In this connection, it should also be noted that within the end zone Z2 the bands 1) are similarly arranged and that the stop abutinents 3?, 91', are so arranged that, as the drill frame 2'2 approaches the line X, the reversing switch arm 96 will be actuated and the drill carriage B caused to reverse its direction, this being accomplished by reason of the For instance, in

7 various connectionsand circuits presently to be more fully described.

"Also mounted near one edge of the table A, is upstanding control block H12 having a long 7 gradually upwardly curving topsurface 33 for engagement with: the lower end of an arm H34 projecting downwardly from the circuit breaker 95' and conventionally connected within the ctr cuitbreaker 95 to the internal mechanism thereof for breaking the circuit when it is urged upwardly by reason of passing over the surface 263 of the control block E82. It should be noted. that the control block W2 is located in suchposition that the arm Hit will pass thereover and produce circuit breaking action within the circuit breaker 95 as the drill frame 22 passes over the line X of the end zone Z1 and a second control block H32, identical with the control blocktGZ, is similarly located promate to the end zone Z1, all for purposes presently more fully appearing.

The carriage B is finally provided with an upstanding conduit pipe 105 for carrying the main current supply line or cable its which projects from the upper end thereof and extends lengthwise above the table through rings l9? slidably' mounted along a messenger cable H38 and is finally connected to a reel H39, which is, in turn, conventionally connected to a main switch H;

By reference to the wiring diagram, Figure 11, it will be seen that the carriage motor 14 is connected through the reversing switch 94 to poles" 92 92 of the relay 92, and one lead from the switch Sun is connected directly to pole 92 of relay 92. One lead or connection of the actuating solenoid H! of relay 92 is connected directly to a step-up amplifier H2, which is, in turn, connected to the photoelectric cell 590. The input leads of the amplifier are connected across the 110 v. D. C. line. The other lead of the relay actuating solenoid HI is connected across the terminals of the circuit breaker 93 and thence to the amplifier HZ. One of the leads from the actuating solenoid H3 of the circuit breaker 93 is connected to the other lead from the switch Sun and the other lead from said solenoid H2 isconnected to the contact point 74 of the resetting switch Sun, the binding post, 89, of which is connected to pole 92 of relay 92. The binding posts or terminals 86, 81', of the resetting switch-actuating solenoid 69 are connected to the leads between the reversing switch 94 and the relay 92, so that, when the relay 92 is closed, the solenoid 69 of the resetting switch will bee'nergized'and, when the relay 92 is open, the solenoid 69 will be de-energized.

A 220 v. three-phase drill motor D is conventionally mounted within the drill housing 53 and is connected through the switch Sue directly to a 220 v. three-phase 180 cycle supply line. In this connection, it may be noted that the supply cable I06 is preferably of the five-wire type, so that both the 110 v. D. C. and 220' v. A. 0. currents can be conveniently supplied therethrough.

The drill feed motor 46 is connected through the switch- Swi directly to the 110 v. D. C. line. The traversing motor 2! is connected across the output leads of the amplidyne generator 91* and the leads from the excitation coils of the amplidyne generator 9| are, in turn, connected across the output terminals of a conventional amplifier H4, which is, in turn, connected to the photoelectric cell"! i. One line input terminal of the am-' olifi'er H4 is connected directly to one sideof the 110 v. D. C. line and the other line input terminal of the amplifier I I4 is connected through the circuit breaker to the other side of the v. D. C. line. The driving motor SF- of the amplidyne is connected directly across the 110 v. D. C. line.

The photoelectric cell llll and its associated amplifier I 14 is so adjusted and biased that, when the light beam is directly upon the edge of a band I) of the template T, a predetermined portion of light will be reflected and a corresponding impulse transmitted by the photoelectric cell l-M to the amplifier H4 and the latter will not transmit any current to the excitation winding of the amplidyne generator 9|. Consequently, the amplidyne generator 9l will not transmit'any current to the traversing motor 2 I. For purposes of the present explanation, it may be assumed that the beam from the light source 99 is focused to follow the righthand margin of the guiding template bands 12 (reference being had to Figure 2) In such case, if the beam travels 01f of the band I) to the right, a lesser amount of light will be reflected into the photoelectric cell HM and the, amplifier bias will be disturbed in such a manner as to produce a negative current output which will be transmitted to the excitation coils of the. ampli-dyn-e generator 9" and will, in turn, produce a proportional amount of current which may be said to be positive in the sense that it will flow through the winding of the traversing motor 2! in such a direction as to cause the latter to shift or traverse the drill frame 22 to the left and thereby move it backv toward the desired path of' movement as defined by the band I). As the drill frame 22 moves back toward the selected band 12, the photoelectric units 6 e which are mounted thereon, will, of course, move in the same direction and ultimately the light beam will tend to move across the righthand margin of the band I), at Which point a greater amount of light will be reflected into the photoelectric cell ltl. The bias of the amplifier IM will accordingly be disturbed in the opposite direction and a corresponding amount of negative current will be transmitted to the excitation; coils of the amplidyne generator 91*, causing the latter to, in turn, generate a corresponding amount of negative current, that is to say, current which will flow through the windings of the traversing motor 2! in such a direction as to cause it to rotate in the reverse direction to that previously described, thereby shifting the drill frame 22 to the left. Because the photoelectric cell It! is mounted directly on the frame 22, any tendency of the device to hunt or over-travel will be substantially eliminated.

When the carriage motor M is energized, it will drive the entire carriage B lengthwise of the table A by means of the wheel l6 and is controlled by the photoelectric cell [06, which is so arranged in reference to its light source 98 that, when the light source impinges u on any one of the spot targets t, light will be immediately reflected into the photoelectric cell 406 and an impulse transmitted to the amplifier H2, which will, in turn, transmit current to the solenoid ill of the relay 9!, the circuit breaker 93 being normally closed. The solenoid III will thereupon Withdraw the contactors of the relay 92, breaking the circuit to the carriage motor l4 and thereby stopping the movement of the carriage B. At the same time, the contactors of the relay 52 will be moved into circuit closing engagement with a secondpair of poles so as to complete the circuit to the drill feed motor 46. It will be noted that the lines to the drill feed motor 46 both pass through the roversing switch Sun and also one line to the drill feed motor 46, in addition, passes through the resetting switch Sws, being connected across the terminals 13, 15. Since the resetting switch 68 is initially in the .position shown in Figure 12, the contact points 13, 15, are in engagement with each other and the circuit to the drill feed motor 46 is thus complete.

When the drill feed motor 46 is initially energized, the drill frame 22 and its associated mechanism is in the position shown in Figure 6, in which the drill head 29 and the drill 53 are in upwardly disposed position. As the drill feed motor 46 begins to rotate, the gear nut 43 is rotated and, since the shaft 4| and the drill head 29 in which it is mounted is relatively free to shift upwardly and downwardly, the shaft 4| is moved vertically downwardly without rotation and the drill head 29 with its associated mechanism is rapidly lowered to the position shown in Figure '7. At this point, the self-centering portion 60 of the drill shield 59 will engage in the aperture h of the template T and will seat itself centrally therein. The drill head 29 and shaft 4| cannot move vertically any further and, as a result, the shaft 4| begins to rotate with the gear nut 43, thereby rotating the gear 47 and the gear nut 48, which, in turn, rotates the drill feed shaft 43. As the drill feed shaft 49 begins to rotate, the driving nut and the driving arm 52 are urged downwardly, thereby feeding the drill point 58 downwardly into the work in the manner shown in Figure 8.

As the drill 53 begins its downward movement, the kick lug 65 moves downwardly away from the toggle arm 63, thereby closing the switch Sun and closing the circuit to the drill motor 45, which thereupon begins rotation, so that the drill point 58 will be rotating at full speed as it bites into the work. The kick lug 64 moves downwardly away from the toggle arm 62 of the reversing switch Sun without affecting it in any way. At the same time, the horizontal projection 90 moves downwardly past the spring-pressed tongue 83 without affecting the mechanism of the resetting switch Swz.

When the drill has reached the downward limit of travel, the kick lug 65 will engage the toggle arm 62 of the reversing switch Sun, tripping the latter and reversing the direction of the leads to the drill feed motor 46, so that the latter will reverse its direction. When the drill feed motor 46 is reversed, the gear nut 43 will also be driven in the reverse direction. Because the shaft 4i tends to shift vertically rather than to rotate and is relatively free to shift upwardly, the reversed movement of the gear nut 43 will cause the shaft 41 and the drill head 29 associated therewith to move rapidly upwardly, carrying the drill point 58 upwardly out of the work to the position shown in Figure 9. Although the drill point 58 is still rotating, such rotation will nevertheless facilitate, rather than oppose, such drill point withdrawing movement. When the drill head 29 and shaft 4i have shifted upwardly to the position shown in Figure 9, further upward movement is impossible. Therefore, the shaft 4| again begins to rotate with the gear nut 43, thereby rotating the gears 41, 48, and drill feed shaft 49. This rotation, of course, is in the reverse direction and, therefore, the drill feed shaft 49 will be reversely rotated and the nut 5|, together with its associated arm 52 and the drill housing 53 mounted thereon, will be shifted upwardly, returning the drill housing 53 to the en- 10 tirely withdrawn original position shown in Figure 6.

As the drill housing 53 returns to its original position, the kick lug 64 will engage the toggle arm 62 of the reversing switch Swi, kicking it back to original position in which the leads to the drill motor 46 are again connected therethrough in a manner such as to cause the drill feed motor to rotate in the downwardly driving direction. At this precise point, however, the horizontal projection will have engaged the tongue 83, which is held against upward swinging movement by the pin 85 and, as a result, the latch arm 89 will. be swung to withdraw the latch bolt I8 from the detent H and the resetting switch bar 70 will be urged outwardly under the influence of the compression spring 16, closing contact between the contact points 12, I4, and breaking contact between the contact points I3, 15. As a result, the circuit to the drill feed motor will be broken and the drill feed motor will come to a stop.

By reason of the closing of the contacts 12, 14, a circuit will be completed across the v. D. C. line through the solenoid I I3 of the circuit breaker 93 and the contactor thereof will be withdrawn from its normally closed position, thereby breaking the circuit from the amplifier I [2 to the solenoid I ll of the relay 92. As soon as the solenoid III of the relay 92 is deenergized, the relay will return to its original position, in which the circuit from the carriage motor to the 110 v. D. C. line is again completed and, at the same time, the circuit to the drill feed motor will be secondarily broken. As the circuit to the carriage motor is completed, the solenoid 69 of the resetting switch Sws, which is connected thereacross, will be energized and, as a result, the solenoid bar Ill will be withdrawn, compressing the spring 16 and bringing the detent Tl into alignment with the latch bolt 18, which thereupon moves upwardly into engagement therewith under influence of the spring 19. The contact between the contact points 12, 14, will thereupon be broken and contact made between the contact points 13, 15, with the result that the portion of the drill feed motor circuit pas-sing through the resetting switch Sw3 will be restored to closed condition, so that when, upon the next cycle of operation, the relay 92 operates to connect the drill feed motor circuit across the 110 v. D. C. line, the drill feed motor 46 will immediately begin to operate. When contact is broken between the contact points l2, 14, the solenoid H3 of the circuit breaker 93 becomes de-energized and the circuit breaker 93 returns to closed position, thereby completing the circuit between the amplifier H2 and the relay solenoid Ill. Before this happens, however, the carriage motor has shifted the carriage B forwardly a suflicient distance, so that the photoelectric unit e is no longer affected by the spot target t which initiated the above described series of operations and, as a result, the carriage will move forwardly again until the electric eye unit e passes over the next successive spot target t. Thereupon, the photoelectric cell I30 will again transmit an impulse to the amplifier H2 and the carriage B will again be stopped for a repetition of drilling operations in the manner just described.

In actual operation, a suitable number of work sheets is placed upon the table A and a template T having the desired spot targets t and bands b is placed thereover in marginally registering relationship. 'The entire stack is then tightly 11 clamped by means of marginal clamping bars H which are secured upon the upper face of the table A by means of bolts I I6. If, for example, it is desired to drill a number of spaced parallel lines of holes, a template of the type shown in Figure 4 may be employed. The automatic drilling machine of the present invention is manually rolled over the table A and the drill frame 22 shifted by manually rotating the lead screw I'I until the drill point 58 is located more or less directly over the first guide hole h of the template T. Thereupon, the main switch H0 is closed and the entire apparatus energized. The photoelectric unit Q will be positioned directly over the first target t and the photoelectric cell I00 will accordingly transmit an impulse through the amplifier H2 in the manner just above described, so that the circuit to the carriage motor I4 will immediately be interrupted and the carriage B will remain stationary while the drill feed motor 46 and ultimately the drill motor D will be energized and the associated mechanism actuated to drill the first hole in the work.

When the drill point 58 has completed its first drilling operation and returned. to initial position, the circuits through which the photoelectric cell I00 functions will be momentarily cut off by the resetting switch Swa in co-operation with the circuit breaker 93 and the carriage motor It will commence rotating and drive the carriage forwardly. The operations of the relay I II and the circuit breaker 93 are so timed in relation to each other that the carriage motor M will have moved the carriage B forwardly and the beam of light from the light source 98 will have moved away from the particular spot target If on which it originally impinged to initiate the above described cycle of operations. Consequently, by the time the resetting switch Siva has returned to latched position and the circuit breaker 93 is again released and returned to circuit closing position, the photoelectric cell I00 will no longer be energized and the circuit motor I4 will drive the carriage B forwardly. During this forward driving movement, the photoelectric unit e will be focused upon the right-hand margin (reference again being had to Figure 2) of the first path-defining band 17 of the template T.

Inasmuch as the holes to be drilled fall in a straight line across the template, the unit follow without difliculty and no particular traversing movement will be necessary until the entire first line of holes has been drilled across the work. As the last hole in the first line is finished, the carriage B will enter the end zone Z1. As the drill point 58 passes over the line X, the actuating arm I04 of the circuit breaker 95 will engage the surface I03 of the control block I02 and the photo-electric unit e will be momentarily rendered inoperative, so that the carriage motor I4 will continue to move along the end zone Z1 and the drill point will travel in a straight line. The band 12 is interrupted or blanked out along this particular portionof its path. As the drill point 58 .passes across the line Y, the circuit breaker actuating arm I04 will again leave the control block I02 and the electric eye unit 6 will come on again. At this point, however, it will pick up the straight continuation :portion b of the band b between the lines Y and X and, as the drill point 58 approaches the line X, the carriage will have moved forwardly to such a position that the actuating member -96-of the re- Vers ng switch 94 will engage and be shifted by the abutment 91, reversing the leads to the carriage motor and thereby reversing the direction of the carriage B, which will then begin to move backwardly along the table in the reverse direction to which it has previously been traveling. The photoelectric unit 6 will continue to follow the continuation portion b of the band b until the drill point 58 again starts to cross the line Y, at which time it will then begin to follow the angular or switchover portion 27 by which it will follow directly into the next succeeding band 1). Of course, the circuit breaker actuating arm I04 will again ride over the control block I02 and the photoelectric unit e will again be momentarily interrupted, but the only efiect of such interruption would be to cause the drill point to over-travel angularly 01f to the right and, since the control circuits are so arranged that the drill point 58 will be shifted back to the left when the beam impinges upon the dark area to the right of the band I), the photoelectric unit e will immediately apply a corrective impulse to the device as soon as it is restored to operative condition after the actuatingarm I04 of the relay passes beyond the control block I82. The following of the prescribed path, as well as the stopping, drilling, and starting operations, will be repeated along the second band b in substantially the same manner as previously described and, as the carriage B finishes this second line, it will pass into the other end zone Z2 wherein its direction will be reversed and the drill frame will be traversed to follow the third band 1), these operations being performed'in substantially the same manner as previously described in connection with the end zone Z1. In this manner, the drill will travel to and fro across the table A stopping, drilling, and starting from target to target along each of the successive guiding bands b until the entire drilling operation has been concluded.

If the holes to be drilled are located in other than straight line relationship to each other, a template T, as shown in Figure 5, may be employed in which the guiding bands will connect the several apertures in a more or less continuously flowing line and the apertures are arranged so that no very sharp change of direction will be required. In designing the template T, the holes should be arranged in a plurality of spaced paths connected in the end zones substantially in the same manner as the template T of Figure 4, so that the drill will be automatically shifted in the end zone to the next succeeding path and will travel to and fro across the table. It will, of course, be understood without necessity of illustration that a multiple spindle drilling head can be conventionally substituted for the single spindle drilling mechanism herein disclosed and a plurality of holes drilled simultaneously each time thte carriage B stops over a particular spot targe t.

If desired, a modified form of automatic drilling machine may be provided which is capable of following a template in which a single guiding band defines the entire path of movement of the drill point. Such modified form of automatic drilling machine is substantially identical in all respects to the drilling machine previously described, including the carriage B, the carriage motor I4, the'traversing motor 2 I, the amplidyne generator 9!, the relay 92, the circuit breaker 93, and the drill frame 22, together with its associated equipment and switches. Instead of the reversing switch 94 and circuit breaker 95, however, an automatic series or controls is substituted. The carriage motor I4 is electrically connected to, and controlled by, a reversing switch II1 having an actuating solenoid H8 and, in addition to driving the carriage is also drivingly connected to a small generator II9, which will generate a current, the voltage of which is directly proportional to the speed of rotation of the carriage motor I4. Similarly, the traversing motor 2I is electrically connected to and controlled by a reversing switch I20, which is provided with an actuating solenoid I2I' and, in addition to its driving connection to the lead screw I1, the traversing motor 2| is drivingly connected to a small auxiliary generator I22 adapted to generate a voltage which is directly proportional to the speed of rotation of the traversing motor 2|. The reversing switches I20 and H1 are also connected with a secondary switch mechanism I28, including two gang-connected double pole, double throw switches actuated by a solenoid I24.

The switch actuating solenoids IIB, I2I, and I24 are connected to a direction indicating and controlling galvanometer G and a circuit-routing control switch S. The direction-indicating and controlling galvanometer G comprises an outer casing I25 suitably mounted in the top plate I3 of the carriage B and has an upwardly presented glass cover I25. Mounted in and extending horizontally across the interior of the casing I25 in downwardly spaced relation to the cover I26, in an insulating disk I21 provided in its upper face with four contactor segments I28, I29, I30, and I3I, which are disposed concentrically and in overlapping relationship to each other in the manner shown in Figure 11 and are electrically connected by means of short lead wires I32 to binding posts I33, which are, in turn, conventionally mounted in the side walls of the casing I25. Also mounted in and extending horizontally across the casing I25 in downwardly spaced relationship to the disk I21, is a magnetic yoke I34 formed preferably of a high permeability alloy, such asAlnico. and having a magnetic p 7.

Rotatably mounted in suitable bearings I35, I36, respectively carried by the bottom wall of the casing I25 and the disk I21, is a conductive shaft I31 projecting upwardly through and a short distance beyond the disk I 21 and being provided at such projecting end with a radially ex? tending conductive pointer or needle I38, which is, in turn, provided at its outer end with a relatively wide slidng contactor shoe I39'adapted for sweeping contact with the upper faces of segments I28, I29, I30, and I3I. The shaft I31 passes concentrically through the magnetic gap g and is there provided with two galvanometer coils I40, I4I, disposed at 90 to each other, the coil I40 also being disposed in the same radial plane as the needle I38. At its lower end, the shaft I31 is rigidly provided with an external dielectric sleeve I42, which is, in turn, provided on its outer face with four axially spaced slip rings I43, I44, I45, I46. Mounted uponand extending upwardly from the bottom wall of the casing I25, is a dielectric post I41 provided with four suitably spaced brushes I48, I49, I50, II, adapted for slidable electrical contacting engagement respectively with the slip rings I43, I44, I45, I46, and being connected by suitable lead wires to binding posts I52, I53, I54, I55, the latter being conventionally mounted in any convenient position in the side wall of the casing I25. The bearing I35 is preferably made ofbronze or other conductive material and pro-,

vided with a downwardly projecting threaded stud I56 adapted to serve as a binding post for the transmission of electric current through the shaft I31 and needle I38 to the segments I28, I29, I30, I3I, depending, of course, upon the position of the needle I38, and similarly the galvanometer coils I40 and MI are connected respectively to the slip rings I42, I43, I44, I45.

The circuit routing control switch S comprises a preferably cylindrical dielectric casing I51 provided in its bottom wall with two suitably spaced binding posts I58, I59, and in its side walls four binding posts I60, I6I, I62, I63, spaced at 90 in-,- tervals from each other, and directly above each such binding post the casing I 51 is provided with inwardly protruding angularly faced bosses I64, Which are, in turn, provided with electro-magnets I65, I68, I61, and I 68, respectively having coils I69, I15, I1I, I12. One end of each of the coils I89, I10, I'1I, I12, is connected in common to the binding post I58. The other ends of each of the coils I69, I16, I1I, I12, are respectively connected to the binding posts I60, I6I, I62, I63.

Mounted in the casing I51 upwardly from the electro-magnets I65, I66, I61, I68, and equidistantly on either side of the binding post I63, are binding posts I 13, I14, which extend through the casing I51 and terminate in stud-like elements I15, I16, for supporting circular conductor seg-- ments I 11, I18, which are, in turn, provided at their extremities with ball-shaped contact points I19, I80, I8I, I82. Also mounted upon the inner face of the casing I51 in the same plane as the stud-like elements I15, I16, is a third stud-like element I83 for supporting a circular conductor segment I84, which is substantially longer than the other two conductor segments I11, I18, and is similarly provided at its ends with ball-shaped contact points I85, I86. By reference to Figure I6, it will be noted that the contact points I19 and I85 are spaced from each other and are located equidistantly on either side of, and above, the center line of the electro-magnet I65. Similarly, the contact points I82 and I86 are spaced from each other and are located equidistantly on either side of, and above, the center line of the electro-magnet I61. Finally, the contact points I 80 and I8I are spaced from each other and are located equidistantly on either side of and above, the center line of the electro-magnet I68. The conductor segment I84 is provided midway between its ends with an arcuate-fa-ced dielectric boss I81, which is located above, and extends symmetrically on opposite sides of, the center line of the electro-magnet I66.

Fixed centrally in, and extending upwardly from, the bottom wall of the casing I51, is a metallic stud I88 provided at its upper end with an electrically conductive spiral spring I 89 connected by a flexible lead wire I90 to the binding post I59. Welded or otherwise rigidly secured to and extending co-axially from the upper end of the spring I 89, is an electrically conductive rod ISI terminating at its upper end in the plane of the contact points I19, I80, I8I, I85, and I86 and being at such end provided with an electrically conductive contactor member I92 preferably having the shape of a truncated sphere and being of sufficient size to simultaneously contact and span the gap between the pairs of spaced contact points I19I85 0r I80-I8I or I82-I86. Just above the point of attachment to the spring I89, the rod I9I' is rigidly provided with an encircling dielectric disk I9I', which is, in turn, provided upon its outer peripheral face with an encircling ring or band 1' formed preferably of soft iron or other highly magnetic material and adapted, upon proper flexure of the spring I89, to impinge against any one of the electro-magnets I65, I66, I61, and I68, depending upon which of such electro-magnets happens to be energized. It wilL-of course, be apparent by reference to Figures 16 and 17 that the spatial relationships of the various parts within the circuit routing control. switch S are such that, when the electro- .magnet I65 is energized, the iron ring T will be attracted thereby and the spring I'89 will accordingly be flexed, so that the rod I9| and its associated contactor member I92 will swing over into circuit-completing engagement with the contact points"I|9-I85. Similarly, when the electro-magnet IE1 is energized, the contactor member I92 will swing into circuit-completing engagement with the contact points I82-I8t, and, when the electro-magnet I68 is energized, the contactor member I92 will accordingly swing over for circuit-completing engagement with the contact points |'8G--I8I. Finally, when the electro-magnet I66 is energized, the conta-ctor member I92 will swing over into engagement with the dielectric boss I81.

The entire control circuit shown in Figure 18 is connected across the line VV as a substitute for that portion of the circuit to the left of line VV in Figure 11. In otherwords, the control circuit in the present modification has to do with the traversing motor and carriage motor only, and

inthis modification, aswell as the modification previously described, thecircuits and mechanisms having to do with the drillmotor and drill feed motor are the same. As has been above stated, the control circuit shown in Figure '18 is designed to cause the drill point 58 to follow in a predetermined path on the template regardless of the direction or curvature of such path and eliminates the expedient of end zones Z1 and Z2, as described in connection with the previous embodiment. v

In order to facilitate an explanation of the operation of the control circuit shown in Figure 18, it is desirable to make certain arbitrary assumptions. Let it be assumed that, for purpose of illustration, the work table upon which the pile of sheets is mounted extends lengthwise in the direction of the large arrow in the upper lefthand corner of Figure .18. Let it be assumed also that the needle I38 lies midway of the contactor segment I29, as indicated in dotted lines in Figure 18. It should be stated parenthetically at this point that this-position of the needle I38 has been arbitrarily chosen for explanatory purposes. Actually, whenever the automatic drilling machine is shut down after use, the needle I38 will re main in whatever position it happened to be at the moment of shut-down. Finally, let it be assumed that the automatic drillingmachine is initially in a .so-called neutral or shut-down condition, in which all the solenoids of the circuit shown in Figure 18 are deenergized. In this neutral position-the bar I 9| of the circuit routing switch S will be vertical and the contactor member I92 will be disposed centrally out of contact with the several contact points thereof. Consequently, the switch III will be in the position shown in Figure '18, whereas the switches I20 and I23 will be in the position shown in dotted lines in Figure 18, having been shifted to that position under influence of the springs which will normally shift such switches into that posi- '16 tion when the solenoids [2| and I24 are deenergized.

For convenient reference in the following explanation, the two brushes of the carriage motor armature will be designated n n, and the brushes of the traversing motor armature will be designated n 11 Let it be assumed in this connection that, when the brush n is positive, the carriage motor I4 will rotate in such a direction as to move the carriage B forwardly (reference bein had to the directional arrow in the upper lefthand corner of Figure 18). Similarly, when the'polarity of the brushes is reversed, so that the brush n is positive, the carriage motor is will rotate in a direction so as to drive the carriage B rearwardly. Similarly, let it be assumed that, when the traversing motor brush n is positive, the traversing motor 2| will rotate in such a direction as to move the drill frame 22 to the right and when the polarityof the traversing motor brushes is reversed, so that the brush n is positive, the traversing motor 2| will rotate in such a direction as to move the drill frame 22 to the left.

The dynamoelectric amplifier or amplidyne generator 9| is, in the present modification, controlled by a photoelectric cell I93 operating through a conventional amplifier I94, which, in turn, draws its input current from the v. A. C. line through a rectifier I95. The photoelectric cell 93 operates in much the same manner as the photoelectric cell IIJI, that is to say, the amplifier circuit I94 is biased, so that, when the beam is directly upon the edge of the path p of the template T", a predetermined portion of the light will be reflected and a corresponding impulse transmitted to the amplifier I94, which impulse is sufficient only to equal and offset the normal potential of the amplifier circuit I95. Consequently, no voltage will be transmitted from the amplifier to the excitation coil of the amplidyne generator 9|. If the photoelectric cell I93 is moved in a direction away from the path p, a lesser proportion of light will'be reflected and a positive potential transmitted by the amplifier to the excitation coil of the amplidyne generator 9|,

With the result that the amplidyne generator ill will transmit a positive potential, the voltage of which is directly proportional to the demand of the photoelectric cell I93. For sake of con venience in the present explanation, it will be assumed that, under the conditions just described, the terminal lead a from the amplidyne generator 9| will be positive and the terminal lead a will be correspondingly negative. By the same token, ii the photoelectric cell I93 is shifted in the opposite direction relatively to the path 1), it will move more or less over into the path p, so to speak, and will pick up a greater proportion of reflected light, which will result in the transmission of a correspondingly greater impulse to the amplifier circuit I94, over-biasing the latter and thereby causing the amplifier circuit I94 to transmit a negative potential to the excitation coil of the amplidyne generator 9|. Such negative potential will cause the amplidyne generator 9| to correspondingly produce a potential proportional to the demand of the photoelectric cell I93 and such potential will flow in the opposite direction to the direction of the potential previously referred to, that is to say, under these latter conditions the terminal lead a will become negative and the terminal lead a will become positive. It will also be noted by reference to Figures 18 and 11 that the line current, to which the carriage motor I4 and the traversing motor 2| may be 17 interchangeably connected through the switch I23, is supplied through the relay 92 and, for purposes of the present description, will be assumed to have the polarity indicated by the notations in Figure 18.

By reference to Figure 18, it will become apparent that the circuit routing switch S in effect has four positions, which may for convenience be designated as positions I, II, III, and IV, in each of which positions the several solenoids and switches of the control circuit are variously disposed and conditioned as follows:

Position I .The solenoid I is energized and the contactor member I92 is accordingly drawn over into engagement with the dielectric boss I81. Consequently, the solenoids II8, I2I, and I24 are all de-energized. The switch II! is in the position shown in full lines in Figure 18. The switches I29 and I23 are in the positions shown in dotted lines in Figure 18. Therefore, the carriage motor I4 is connected to the line and the brush n thereof is positive, so that, when the entire circuit is energized by closing a master switch III], the carriage motor I4 will operate to drive the carriage B forwardly at constant speed. The traversing motor 2! will be connected across the amplidyne generator 9| and the terminal lead :1 thereof will be connected to the brush n so that, when the photoelectric cell I93 is off the line to the right (i. e. receives insuflicient light), the terminal a will be positive and the traversing motor 2| will rotate in such a direction as to shift the drill frame 22 leftward, bringing the apparatus back to the edge of the line, so to speak. Conversely, when the photoelectric cell I93 is off to the left of the edge of the line (i. c. more fully above the line, hence receives excess of light), the terminal a will be negative and the direction of current in the armature of the traversing motor 2| will flow in the opposite direction, with the result that the traversing motor 2| will rotate in the opposite direction, shifting the drill frame 22 to the right and again bringing the apparatus back on the edge of the line.

Position II.-The solenoid I69 is energized and the contactor member I92 is swung over into circuit completing engagement with the contact points I19, I85. Consequently, the solenoid H8 is de-energized and the switch III is in the position shown in full lines in Figure 18. The solenoids I 2| and I24 are now both energized and the switches I20 and I23 will be shifted against the tension of their respective springs into the position shown in full lines in Figure 18. As a result, the traversing motor 2| will now be connected across the line in such a manner that the brush n thereof is positive and the drill frame 22 will be moved leftward at constant speed. The carriage motor I4 is connected across the amplidyne generator 9| in such a manner that the terminal a is positive, the carriage motor I4 of the carriage motor I4. Therefore, when the terminal a, is positive, the carriage motor I4 will rotate in such a direction as to shift the drill carriage B rearwardly and, conversely, when the terminal a is negative, the carriage motor l4 will rotate in such a direction as to shift the drill carriage B forwardly. As will presently be more fully explained, the control circuit is in this position II when the general direction of the path p extends angularly to the left within the range of direction designated as quadrant II (see directional reference arrow, upper lefthand corner, Figure 18). Consequently, the deviation of the photoelectric cell I93 from the line will,

18 in a manner of speaking, be either in the forward or rearward directions and the corrective action to return the apparatus to the line will be applied by the carriage motor I4.

Position IIL-The solenoid H2 is energized and the contactor member I92 will accordingly be swung over into circuit completing engagement with the contact points I80, I8I. Consequently, the solenoids H8 and |2I will be energized and the solenoid I24 will be deenergized. Therefore, the switch I20 will be in the position shown in full lines in Figure 18 and the switches III and I23 will be in the positions shown in dotted lines in Figure 18. The carriage motor I4 will thus be connected to the line in such a manner that the brush n thereof is positive and the carriage motor I4 will rotate in such a direction as to drive the carriage B rearwardly at constant speed. Similarly, the traversing motor 2| will be connected across the amplidyne generator 9 I, so that the terminal a is connected to the brush n Therefore, the traversing motor 2| will shift the drill frame 22 to the right when the terminal a is positive and to the left when the terminal a is negative consistently with the reversal in the direction of movement of the carriage B.

Position I V.-The solenoid III is energized and the contactor member I92 is swung over into circuit completing engagement with the contact points I82, I86. Consequently, the solenoid |2I is de-energized and the solenoids I I8 and I24 are energized. Therefore, the switches III, I29, are both in the positions shown in dotted lines in Figure 18 and the switch I23 is in the position shown in full lines in Figure 18. The traversing motor 2| is thus connected across the line with the armature brush n positive, so that the drill frame 22 will be driven to the right at constant speed. The carriage motor I4 is connected to the amplidyne generator 9| with the terminal lead a thereof connected to the armature brush n ,of the carriage motor I4. When the terminal lead a is positive, the carriage motor I4 will rotate in such a direction as to drive the carriage B forwardly and, conversely, when the terminal a is negative, the carriage motor I4 will rotate in the opposite direction so as to drive the carriage B rearwardly.

It will be apparent that the actual direction .of movement of the drill point 58 Will be the resultant of the forward and rearward movement of the carriage B and the transverse shifting movement of the drill frame 22. For example, suppose the path p of the template T" (reference being had to Figure 13) includes a portion H extending off to the left at an angle of 45 to the forward direction, the drill point 58 would be caused to traverse or follow this path by movement of the carriage B forwardly at constant speed and simultaneous movement of the drill frame 22 leftwardly at the same speed. If the path 79 extended straightforwardly with no deviation to the left or right, the traversing motor 2| would be stationary and the entire movement produced by the forward travel of the drill carriage B. If the path 10 deviated to the right of the forward direction, the traversing motor 2| would necessarily have to operate to shift the drill frame 22 to the right at a speed sufficient to produce a resultant direction of movement of the drill point 58 in the desired direction. Obviously, by various appropriate combinations of speed and direction of the carriage motor I4 and the traversing motor 2|, the drill point 58 r 19" may be caused to move in any desired direction over the template T".

Depending upon speed and direction of rotation of the carriage motor I I and traversing motor 2|, the auxiliary generators H9 and I22, which are respectively driven thereby, will gen crate currents the potential and direction of which correspond to the speed and direction of rotation thereof and will produce correspond ingly proportionate fluxes the galvanometer coils I40, MI, and thereby the needle I 38 will be magnetically oriented so as to point substantially the direction of movement of the drill point 58 at any given instant. The electrical contact between the several segments I28, I29, I30, I3I, and the contactor shoe I39 of the needle I38 serves as a switch for optionally energizing any one of the solenoids I69, I10, I-II, I12, depending upon the position of the needle I38. Consequently, when the needle I38 points in any direction within quadrant I, the circuit routing switch S will assume position I. Similarly, when the needle I38 points in any direction lying within quadrant II, the circuit routing switch S will be shifted into position II. Similarly, when the needle I38 points in any direction lying within quadrant III, the circuit routing switch S will be shifted into position III. Finally, when the needle I38 points in any direction lying within quadrant IV, the circuit routing switch S will be shifted into position IV. I

It will be obvious that when the desired direction of movement of the drill point 50 is more or less close to 45 to the right or left in either the forward or rearward direction, it will make little difierence whether the carriage motor I I is connected to the line and is operating at constant speed with the traversing motor 2| correspondingly connected to the amplidyne generator 9i for applying the to-and-fro corrective movement under control of the photoelectric cell I93 or whether, contrariwise, the traversing motor 2| is connected to the line for constant speed movement and the carriage motor I4 is correspondingly connected to the amplid-yne generator 9| for creation of to-and-fro corrective action under control of the photoelectric cell I93. Because this is true, it becomes possible to avoid an otherwise undesirable cycling tendency, that is to say, a rapid intermittent switching back and forth within the switches III, I20, and I23 when the needle I33 hovers over any one of the four boundaries between the different quadrants. The segments I28, I29, I30, I3I, are of sufficient ar'cuate length so as to overlap each other slightly in the area of these 45 directions, that is to say, in the area of the boundary line between the respective quadrants.

Suppose, for example, the drill point 58 is following a path which lies within quadrant II and the needle I38 is moving back and forth across the segment I28. As the direction of the line being followed swings past the 45 point and, in a manner of speaking, crosses the boundary into quadrant I, the needle I38 will likewise swing in such a manner as to indicate this directional change and continue to point in the direction of the path being traversed. If the direction of path is changing, that is to say, if the path is curved, such as, for example, the section K (reference being had to Figure 13), the needle I38 will swing forwardly and the contact shoe I39 will ride forwardly along the segment I28 until it is simultaneously in contact with the segments I28 32nd I29 in the ir eg'lbh of their Yespective overlapping portions. As has been previously explained, when the shoe I39 is in contact with the segment I28, the solenoid I69 will be correspondingly energized and the contactor member I92 of the switch S will be in position 11. As the contactor shoe I39 also moves into contacting engagement with the segment I29 in the region of segmental overlap, the solenoid III] will also become energized, but the contactor member I92 will continue to remain in position II as long as the solenoid I69 remains energized. Consequently, as the needle I38 hovers back and forth across the boundary line between quadrant I and quadrant II, there Will be no rapid switching back and forth of the various elements of the control circuit. When, however, the needle I38 passes forwardly entirely beyond the segment I23, so that the contactor shoe I39 is in contacting engagement only with the segment I29, the solenoid I69 will immediately become de-energized and, since the solenoid III) is already energized and remains so, the contactor member I92 will immediately swing over into position I and the various elements of the control circuits will assume the relationships consistent with position I, as above described.

Finally, if the needle I38 begins to swing back and again moves into the region of segmental overlap between the segments I29 and I28, the reverse condition will obtain. The solenoid I10 will remain energized and hold the contactor member I92 in position I as long as the contactor shoe I39 remains in the region of segmental overlap and, even though the solenoid I69 again becomes energized, it will still not pull the contactor member I92 into position II until the contactor shoe I39 has finally moved completely away from, and out of contact with, the segment I29 so as to de-energize the solenoid I70 and release the contactor member I92. It will be noted that the segment I29 is in a sense a dummy segment in that the contactor member I92 does not perform any circuit completing function when the solenoid I'Il) is energized inasmuch as this contactor element I19, when in position I, is held against the dielectric boss I87 and, as a result, all three of the switch actuating solenoids H8, I2I, and I24 are de-energized. This segment I29, however, does serve to bridge the gap between the segments I29 and I30 for purposes of providing regions of segmental overlap and thereby prevent cycling of the various elements of the control circuit as the needle I33 and its associated contactor shoe I39 hover across the proximate ends of the segments I28, I30. It it is desired 'to set the automatic drilling apparatus in operation over the template T" having an irregular and tortuous path 7), the carriage B is moved over the particular segment of the path along which drilling operations are to be commenced, say, for instance, the section J of the path p. The lead screw Ii can be manually rotated or otherwise turned to move the drill frame 22 to the right or left, as the case may be, until the photoelectric cell I93 is focused upon the righthand edge (1 of the path p. For purposes of illustration, it may be assumed that the needle I38 is in the straight forward Figure 18.

When the master switch III] is closed and the entire apparatus energized, the contactor member I92 will immediately 'move into position I, since "the contactor shoe I39 of the needle I38 is position shown in dotted lines in in contactive engagement with the segment I29. The carriage motor I4 therefore begins to drive the carriage B forwardly at constant speed and the first increment of movement in this direction will shift the electric eye I93 forwardly away from the edge 11 of the path p, so that it will momentarily receive insuflicient light. Consequently, the terminal a of the amplidyne generator 9I will become positive. As has been above pointed out, in position I the traversing motor 2I is connected to the amplidyne generator 9I in such a manner that, when the terminal a becomes positive, the traversing motor 2| will shift the drill carriage B to the left, thereby setting a corrective action which will bring the drill point 58 back on the line, so to speak. Although, for purposes of description, these respective movements of the carriage motor I4 and the traversing motor 2I are treated as incremental, in actual practice both motors are in more or less continuous operation and the rate of rotational speed of the motors varies differentially from moment to moment so as to produce a closely integrated resultant movement of the drill point 58 in close pursuance of the edge at of the path 1). Since the needle I38 was initially pointing straight forward, that is to say, in the center of quadrant I, the carriage motor I4 will initially shift the photoelectric cell rather far forwardly of the edge at of the path 11 and a relatively large surge of current will be produced by the amplidyne generator 9I so as to produce a correspondingly rapid rotation of the traversing motor 2I. Immediately the auxiliary generator I22 sets up a relatively large flux in the galvanometer coil I4I to offset the flux in the coil I49 produced by the current generated in the auxiliary generator II9. This interaction of magnetic flux within the controlling galvanometer G will operate to swing the needle I38 downwardly into the position shown in full lines in Figure 18.

Since the angle of deviation of the section J of the path 1) has, for purposes of illustration, been arbitrarily taken to be 65, the needle I38 will swing 65 to the left of its original position and will come to rest in quadrant II, thereupon causing the circuit routing switch S and the other related switches III, I20, and I23 to shift into the relationship above designated as position II,

whereupon the traversing motor 2| is transferred over to the line and begins to shift the drill frame 22 leftward at constant speed, while the carriage motor I4 is transferred over to the amplidyne generator 9| and takes up the function of to-and-fro shifting movement under the control of the photoelectric cell I93, so as to maintain the drill point 58 on the line, so to speak. As the drill point 58 moves upwardly and begins to follow the arcuate section K of the path p, the needle I38 will swing back again and the drill oint 58 will follow the necessary changes in direction until finally it is moving along the straight-forward section L of the path p. The needle I38 will, of course, by this time have swung into straightforward position in quadrant I and the circuit routing switch S will be correspondingly shifted into position I. The carriage motor I4 will again be switched back onto the line and will propel the carriage B forwardly at constant speed.

During this particular phase of operation, there will be no deviation in direction and the traversing motor 2| will be momentarily inoperative because the output of the amplidyne generator 9I will remain at zero so long as the photoelectric cell I93 remains focused along the edge 11 of the path p. As the drill point 58 continues to move forwardly and comes into the reversely curved portion M of the path p, the needle I38 will swing over into quadrant IV and the carriage B will com.. mence to move rearwardly. It will be noted that the edge d of the path p is on the right-hand side of the path during the previously described conditions of forward travel of the carriage B, but, as the path p turns back upon itself, the edge (1 will ultimately be on the lefthand side of the path. This, of course, makes it necessary that the direction of current flowing out of the amplidyne generator 9I be reversed, so to speak, for positions III and IV. By reference to the foregoing analysis of these positions, however, it will be evident that the switches II'I, I29, and I23 operate to effect the necessary reversal of polarity, so that, on the reversely bent portions of the path p, the photoelectric cell I93 will still continue to follow the same edge d.

It will, of course, be understood that wherever it is necessary to drill a hole into the work, a suitable target will be located adjacent to the path p in identically the same manner as previously described in connection with the first embodiment above discussed, and the stopping, starting, and hole drilling functions of the photoelectric cell I99, the relay 93, and the switches SW1, SW2, and SW3 will be identical in the present modification as well.

It should be understood that changes and modifications in the form, construction, arrangement, and combination of the several parts of the automatic drilling machine may be made and substituted for those herein shown and described without departing from the nature and principle of my invention.

Having thus described my invention, what I claim and desire to secure by Letters Patent is:

1. An automatic drilling machine comprising a work table having spaced parallel rails, a carriage mounted upon the rails for to-and-fro travel lengthwise over the table, drilling means mounted in the carriage for transversely shiftable movement thereacross, a carriage motor mounted on and carried by the carriage for propelling the carriage lengthwise across the table, a traversing motor mounted on the carriage for shifting the drilling means transversely across the carriage, a source of constant voltage, a source of variable voltage, and means for selectively switching the carriage motor and traversing motor alternately from one voltage source to the other in such a manner that when the carriage motor is connected to the source of constant voltage then the traversing motor is connected to the source of variable voltage and when the carriage motor is connected to the source of variable voltage then the traversing motor is connected to the source of constant voltage.

2. An automatic drilling machine comprising a work table having spaced parallel rails, a carriage mounted upon the rails for to-and-fro travel lengthwise over the table, drilling means mounted in the carriage for transversely shiftable movement thereacross, a carriage motor mounted on and carried by the carriage for propelling the carriage lengthwise across the table, a traversing motor mounted on the carriage for shifting the drilling means transversely across the carriage, a source of constant voltage, a source of variable voltage, means for selectively switching the carriage motor and traversing motor alternately trom. onevoltage; Source to the other in such, a Ina-linerthat when the carriage motor is connected; to the source of constant voltage then the traversing motor is; connected to the source of variable voltage and when the carriage motor is connected to the source of variable voltage then the traversing motor is, connected to the source of constant voltage, a template having pathdelineating indicia inscribed upon one of its faces, and photoelectric means sensitive to said pathdelineating indicia for controlling the operation of said switching means.

3. An automatic drilling machine comprising av work table having spaced parallel rails, a carriage mounted upon the rails for to-and-iro travel lengthwise over the table, drilling means mounted in the carriage for transversely shiftable movement thereacross, a carriage motor mounted on and carried by the carriage for propolling the carriage lengthwise across the table, 3

a traversing motor mounted on the carriage for Shifting the drilling means transversely across the carriage, a source of constant voltage, a source of variable voltage, means for selectively switching the carriage motor and traversing motor alternately from one voltage source to the other in Such a, manner that when the carriage motor is connected to. the source of constant voltage then the traversing motor is connected to the source of variable voltage and when the carriage motor is connected to the source of variable voltage then the. traversing motor is connected to the source of constant voltage, a template having path-delineating indicia inscribed upon one of its faces,

photoelectric means sensitive to said path-delineating indicia connected to the source of variable voltage to. control the output thereof, and means simultaneously affected by the rates of rotation of both the carriage motor and the traversing motor tov sense the resultant eifect thereof upon the direction of movement of the drilling means, said last-named means being connected to the switching means for controlling the action thereof responsive to predetermined changes in direction of movement of the drilling means.

,4. An automatic drilling machine comprising a work table having spaced parallel rails, a carriage mounted upon the rails for to-and-fro travel lengthwise over the table, drilling means mounted in the carriage for transversely shiftable movement thereacross, a carriage motor mounted on and carried by the carriage for propelling the carriage lengthwise across the table, a traversing motor mounted on the carriage for shifting the drilling means transversely across the carriage, a source of constant voltage, a source of variable voltage, means for selectively switching the carriage motor and traversing motor alternately from one voltage source to the other in such a manner that when the carriage motor is connected to the source of constant voltage then the traversing motor is connected to the source of variable voltage and when the carriage motor is connected to the source of variable voltage then the traversing motor is connected to the source of constant voltage, a template having pathdelineating and target-forming indicia inscribed upon one of its faces, photoelectric means sensitive to said path-delineating indicia connected to the source of variable voltage to control the output thereof, means simultaneously affected by the rates of rotation of both the carriage motor and the traversing motor to sense the resultant eflect: thereof upon the direction of movement of the drilling means, said iast-named means being til connected to. the switching means. for controlling e action thereof, responsive to predetermined changes direction of movement of the drilling means, and second photoelectric means sensitive tosaid targetefgorming indicia on the template for stopping carriage movement at predetermined locations and initiating a drilling operation by thedrilling means.

5, An automatic drilling machine comprising a work; table, having spaced parallel rails, a carriage mounted upon the rails for to-and-fro travel. lengthwise over the-table, drilling means mounted in the carriage for transversely shiftable movement thereacross, a carriage motor mounted on and, carried by the carriage for propelling the carriage lengthwise across the table, a traversing motor mounted on thecariage for shifting the drilling means transversely across the carriage, a source oiconstant. voltage, a source of variable voltage, means for selectively switching the can ridge motor and traversing motor alternately from one Voltage source to the other in such a manner that when the carriage motor is connected to. the source of constant volta e then the motor is, connected to the. source oi variable; voltage and when the carriage motor is connected to the source of variable voltage then the traversing motor connected to the source of constant, voltage, a template having pathdelineating and target-forming indicia inscribed upon one of its faces, photoelectric means sensitive to said path-delineating indicia connected to the source of variable voltage to control the output thereof, means simultaneously affected by the rates of rotation of both the carriage motor and the traversin motor to sense the resultant effect thereof upon the direction Of movement of the drilling means, said last-named means being connected to. the switchingmeans, for

= controlling, the action thereof responsive to predetermined changes in direction of movement of the drilling me ns, se ond photoel c ric m an sensi ive to said target-formin in icia on the template for stopping carriage movement, at predetermined locations and initiating a drilling operation by the drilling means, and m an actuated by the drilling means, upon completion of a drilling operation for setting the carriage in motion, again.

.6. An automatic drilling machi e. comprisin a w rk. ta le having spaced p rall l ra l a ca riage moimted' upon the rails for to and fro travel lengthwise over the table, drillin means mounted in the carriage for transversely shiftable movement thereacross, a carriage motor mounted on and carried by the carriage for propelling the carriage lengthwise across the table, a traversing motor mounted on the carriage for shifting the drilling means transversely across the carriage, source of constant voltage, a source of variable voltage comprising an amplidyne motor generator set, electronic control means connected to the amplidyne motor-generator set for varying voltage output thereof, and means for selectively switching the carriage motor and traversing motor alternately from one voltage source to the other in such a manner that when the carriage motor is connected to the source of constant voltage then the traversing motor is connected to the source of variable voltage and when the carriage motor is connectedto the source of variable voltage then the traversing motor is connected to the source of constant voltage.

7. An automatic drilling machine comprising a work table having spaced parallel rails, a car- 25 riage mounted upon the rails for to-and-fro travel lengthwise over the table, drilling means mounted in the carriage for transversely shiftable movement thereaoross, a carriage motor mounted on and carried by the carriage for propelling the carriage lengthwise across the table, a traversing motor mounted on the carriage for shifting the drilling means transversely across the carriage, a source of constant voltage, a source of variable voltage, and means for selectively switching the carriage motor and traversing motor from one voltage source to the other depending upon the quadrant in which the direction of resultant movement of the carriage lies in such a manner that when the carriage motor is connected to the source of constant voltage then the traversing motor is connected to the source 26 of variable voltage and when the carriage motor is connected to the source of variable voltage then the traversing motor is connected to the source of constant voltage.

WILLIAM T. BAYLESS.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,069,995 Anderson Aug. 12, 1913 1,269,481 Matthews June 11, 1918 2,172,313 Young Sept. 5, 1939 2,262,295 Moore Nov. 11, 1941 2,323,126 Goddard June 29, 1943 

